The present invention relates to a sewing machine control box.
The structure of a conventional sewing machine control box of the same general type to which the invention pertains is shown in FIGS. 4A and 4B. In FIGS. 4A and 4B, reference numeral 1 designates an adjustable speed clutch motor having an output shaft 1a, which is a driving source for the sewing machine; 2, a control box including a printed circuit board 3, a lever section 4 and a transformer 5; 6, a sewing machine driving motor frame; 7, a mounting plate secured to the frame 6 on which the control box 2 is mounted; 8, a cover, secured to the sewing machine driving motor frame 6 with screws, for protection of a motor power source connecting section; 9, a connecting cord for supplying voltage to the primary lead wire of the transformer 5; and 10, connectors for a detector, a sewing machine solenoid, etc.
In the above-described sewing machine driving control box, the number of elements on the printed circuit board 3 is decreased as it employs a hybrid, gate array or microcomputer technique. Therefore, the printed circuit board 3 can be miniaturized.
However, since the conventional control box includes not only the printed circuit board 3 but also the transformer 5, the electronic components on the printed circuit board 3 can be damaged by heat generated by the transformer 5, and hence it is impossible to position the printed circuit board 3 and the transformer 5 adjacent to each other. Consequently, the space within the control box must be quite substantial, and the control box is necessarily large both in volume and in weight.
In U.S. Pat. No. 3,885,175, there is disclosed the structure of a motor in which a housing is provided on an end face of the frame 6 and a transformer is incorporated in the housing. However, the structure is not of the type where the printed circuit board is incorporated in the housing. Accordingly, the above-described disadvantages of the conventional control box are not overcome by the structure disclosed in this patent.